Marine Vessel Station Keeping Near Objects Using Proximity Sensing
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Solution Overview
Problem
Current marine vessel control systems face challenges in accurately maintaining a selected position and orientation, especially in proximity to objects, due to limitations in GPS signal fidelity and latency in control outputs, which can lead to inaccurate positioning and potential collisions with structures like docks or seawalls.
Innovation Solution
A system that integrates a global positioning system (GPS) and proximity sensors to determine the marine vessel's position and orientation, allowing the controller to choose between GPS and proximity data for precise positioning and orientation maintenance, using thrust commands to adjust the vessel's position and orientation based on the selected mode, thereby ensuring accurate station keeping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS is used for position determination, then global positioning capability is provided, but signal fidelity and latency cause inaccurate positioning near objects
Solution Approach 1:
The system segments the positioning function by using different sensors for different operational contexts: GPS for open water positioning and proximity sensors for near-object positioning. This segmentation allows each sensor to operate in its optimal environment, resolving the contradiction between global coverage and local accuracy.
Solution Approach 2:
Proximity sensors act as intermediaries between the vessel and objects when GPS becomes unreliable. The system transitions from direct GPS-based positioning to proximity-sensor-based positioning near objects, using the proximity sensors as a mediating measurement system that provides accurate local positioning data.
2Measurement precision
If proximity sensors are used near objects, then positioning accuracy improves, but system complexity increases due to sensor integration
Solution Approach 1:
The controller is designed with multi-functionality, capable of processing both GPS data and proximity sensor data, and automatically selecting the appropriate data source based on operational context. This universal controller reduces overall system complexity despite multiple sensors by consolidating processing logic in a single component.
Solution Approach 2:
The system dynamically switches between GPS and proximity sensor data sources based on the vessel's proximity to objects. This dynamic adaptation allows the system to maintain simplicity by using only the necessary sensor type for each situation, rather than continuously processing all sensor inputs.
3Productivity
If GPS data is used for station keeping, then global position maintenance is achieved, but control resolution is insufficient in close proximity to structures
Solution Approach 1:
The system applies local quality by using high-precision proximity sensors specifically in the local context of near-object operations, while relying on GPS for global context. This localized enhancement of measurement quality provides the necessary control resolution only where GPS fails, optimizing both productivity and precision.
4Reliability
If the controller switches between GPS and proximity data, then positioning reliability improves, but response time increases due to data selection processing
Solution Approach 1:
The controller continuously monitors proximity to objects and pre-determines the appropriate data source before switching is needed. This preliminary assessment allows for seamless transitions between GPS and proximity sensor data without significant processing delays, maintaining both reliability and rapid response.
Data Source
AI summary
A system for maintaining a marine vessel in a body of water at a selected position and orientation includes a global positioning system that determines a global position and heading of the vessel and a proximity sensor that determines a relative position and bearing of the vessel with respect to an object near the vessel. A controller operable in a station keeping mode is in signal communication with the GPS and the proximity sensor. The controller chooses between using global position and heading data from the GPS and relative position and bearing data from the proximity sensor to determine if the vessel has moved from the selected position and orientation. The controller calculates thrust commands required to return the vessel to the selected position and orientation and outputs the thrust commands to a marine propulsion system, which uses the thrust commands to reposition the vessel.